### B-integral

Value of B-integral for material of given thickness $$z$$, wavelength of radiation and position-independent (maximal) intensity $$I_\mathrm{max}$$: $$B=\frac{2\pi}{\lambda}\intop_0^{z}n_2I(z)\mathrm{d}z'=\frac{2\pi n_2 I_\mathrm{max} z}{\lambda}.$$ Reported values of nonlinear refractive index $$n_2$$ at the corresponding wavelenghts given below. For wavelenghts in the given range, value of $$n_2$$ is interpolated. For wavelenghts outside the region, $$n_2$$ at the closest wavelength is used.